Aging changes in the male reproductive system This site provides a useful description of changes that often happen as men age. "Aging changes in the male reproductive
system may include changes in testicular tissue, sperm production, and
erectile function. These changes usually occur gradually. Unlike
women, men do not experience a major, rapid (over several months)
change in fertility as they age (like menopause). Instead, changes occur
gradually during a process that some people call andropause."

Men and Aging5 Things Men Fear Most About AgingBy Paula Spencer Scott, Caring.com senior editor "Worried about getting old? Who isn't -- except perhaps those who are already unmistakably there."